Grinding-mill.



J. WALKER. GRINDING MILL. APPLICATION mum mm. 17, 1909.

,972 mama Mar. 1, 19m.

2 BHEETS-BHBBT 1.

m m" m A2 v r 4% J. WALKER. GRINDING MILL. APPLICATION FILED MAR. 17,1909.

Patenteol a1". 1, W110.

JOHN WALKER, OF BOSTON, MASSAGHUSET TS, ASSIGNOR 'IO JOHN WALKER MACHINECOMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

GRINDINGPMILL.

950 ,9 72. Specification of Application filed. March 17 T 0 all whom itmay concern:

Be it known that I, J OHN WALKER, of Boston, in the county of Suffolkand State of Massachusetts, have invented certain new and usefulImprovements in GrindingMills, of which the following is aspecification.

This invention relates to machines for triturating, mixing, andlevigating material of a more or less oily nature, such as cocoa, andrelates particularly to grinding mills for the manufacture of chocolatefrom the cocoa bean.

The invention is embodied in a mill comprising a fixed outer member orshell having an inlet for the crude material at one end, and an outletat the opposite end; and an inner rotary member or runner shaped toconform closely to the interior of the outer member, the opposedlevigating faces of the outer and inner members being in close proximityto or rubbing contact with each other, and being of tapering orfrusto-conical form, so that the levigating surfaces can be givenabsolutely accurate relative posi tions by shifting or adjusting onemember longitudinally relatively to the other. The levigating face ofone of the members, preferably that of the inner member, has a dress-composed of helical furrows, separated by helical smooth surfaces. Inaccordance with my invention, the inclin ation o f said f rows ischanged bettfii n ta d, h.. l l V lllllfi y clined f act on '"thecrudematerialintroduced at the inlet and tend to. force the same at arelatively api'dy rate toward the outlet end while re ucmthe material,the inclination of the furrows being changed between the inlet andoutlet to form delivering portions extending from a point between theinlet and outlet to the outlet, whereby the movement of the materialtoward the outlet, caused by the-feeding portions, i s ehecl e were e abackpre sure 011 said mate a and a iegimding tlie'feeding portions, thematerial being additionally ground and conducted to the outlet end ofthe mill by the delivering portions, and at the same time subjected tore tarding pressure thereby.

Of the accompanying drawings, forming a part of thisspecificat1on,-Figure 1 repre sents a longitudinal section showing thetwo members operatively related to each other.

Patented Mar. 1, 1.910.

Serial No. 483,895.

Letters Patent.

t Fig. Qrepresents a side elevation of the inner member. Fig. 3represents a longitudi nal section of the outer member, the inner memberbeing removed. Fig. t represents a section on line 4c-4c of Fig. 2. Fig5 represents a section on line 5-5 of Fig. 2.

The same reference characters indicate the same parts in all thefigures.

In a pending application for Letters Patent of the United States, for animprovement in grinding mills. filed by me October grinding mill whichincludes a fixed outer member or shell, and a rotatable inner member orrunner, together with suitable means for supporting said members,adjusting one endwise relatively to the other, rotating the innermember, and cooling the members while they are in operation.

It will be understood that the improvement hereinafter described andclaimed, relating to the dress of the levigating surface of one of themembers, may be applied to a mill of the general construction shown inthe above mentioned application. I therefore deem it unnecessary toillustrate and describe in this application anything more than issutlicient to afford an understanding of the present improvement.

In the drawings, which represent an embodiment of my invention which Ihave shown for purposes of illustration, 12 represents the fixed outermember or shell, which is rigidly supported in any suitable manner,

and has a tapered or frusto-conical interna grinding and levigatingsurface.

, At thelarger end portion of the member 12 is an inlet 13 for the crudematerial. The smaller end of the member 12 constitutes an outlet for theground material, which may be conducted away from said smaller end by asuitable guide or spout, as shown in the prior application abovementioned.

1 1 represents the rotary inner member or runner, which is locatedwithin the outer member 12, and has an external grinding and levigatingface. Each of said grinding faces is tapered, and the two members are sorelated as to leave between their opposing surfaces an annular conicalworking space or crevice extending from end to end of the outer memberand runner, the material to be treated being fed to one end of saidcrevice and ejected from the opposite end after 29, 1908, Serial No.460,011, I have shown a l passing through the entire length of thecrevice between the opposing faces of the members.

I provide the levigating face of one of the members, and preferably therotary inner member 14, with a dress which is composed of alternatingfurrows 15 and intermediate smooth portions 16, said furrows being theequivalent of screw threads of a steep pitch, one side of each furrowbeing substantially at right angles to the axis of the runner, While theopposite side is inclined to said axis, as shown in Fig.

The portions of the furrows which coincide with the supply inlet 13 mayhave'the. rectangular form shown in Fig. 5, the general form of thefurrows being preferably substantially as shown and described in theabove mentioned application.

In carrying out the present invention, I change the inclination of thefurrows and the intermediate smooth surfaces between the inlet andoutlet portions of the mill, so that said furrows, instead of extendingat a uniform inclination from the inlet to the outlet of the mill, havea different or backward inclination at the outlet end portion, thedirection of the furrows changing'preferably at a Zone indicated by thedotted line .ra in Fig. 4. The direction of rotation of the inner memberis such that the pertions of the furrows between the line and the inlet30, said portions occupying preferably about two-thirds of the length ofthe levigating surface, and being hereinafter referred to as the feedingportions, have a tendency to feed the material at a relatively rapidrate from the inlet toward the outlet, while reducing the same. Thedifference between the inclination of the said feeding portions and theinclination of the portions of the furrows between the line and theoutlet end, these being hereinafter referred to as the deliveringportions, is such that the said. delivering portions oppose or retardthe movement of the material toward the outlet, and thus create a backpressure on the material being acted on by the feeding portions. Thisback pressure causes a repeated grinding of the material by the feedingportions of the furrows and the intermediate smooth surfaces, thematerial being gradually forced along the delivering portions of thefurrows by its accumulation between the levigating surfaces, the saiddelivering portions at the same time subjecting the material to aretarding pressure which causes it to be repeatedly ground between allparts of the 'levigating surfaces. The delivering portions of the.furrows extend to and through the smaller end of the levigating surfaceon which they are formed, so that the ground material issues throughthem at the outlet end of the mill.

As already stated, the portion of the levigating surface occupied by thefeeding portions of the furrows is preferably of considerably greaterlength than that occupied by the delivering portions of the furrows, sothat the pressure of the feeding portions of the material tending toforce it to the outlet end, overcomes theretardation caused by thechanged inclination of the delivering portions, and thus causes thedelivery of the ground material at the outlet end through the deliveringportions.

It will be seen from the foregoing that my present invention resides inthe described change of the inclination of the furrows at points betweenthe inlet and outlet of the mill, and preferably nearer the outlet thanthe inlet, and the continuation of the delivering portions so that theyconstitute colleetively the outlet of the mill. The back pressure due tothe delivering portions of the furrows enables me to dispense with thesmooth or unfurrowed portions of the levigating surfaces at the outletend portion of the mill, shown in the above mentioned application, sothat the material issues from the mill with less resistance than wouldbe the case if said smooth portions were employed, and less power isrequired to rotate the inner member and force the material through themill, the material being at the same time effectively reduced.

I claim:

A mill for grinding materials, such as cocoa, said mill comprising afixed outer member having an inlet for the crude material at one end,and an outlet for the ground material at the other end, and a rotatableinner member in rubbing or levigating contact with the outer member, oneof said members having a dress composed of helical furrows andintermediate smooth portions, the inclination of which is changedbetween the inlet and outlet.

In testimony whereof I have afiixed my signature, in presence of twowitnesses.

JOHN ALKER.

WVitnesses C. F. BROWN, P. W. PEZZETTI.

